Kobe Earthquake Research Articles

Role of Civil Society in Sustainable Urban Renewal (Machizukuri) after the Kobe Earthquake

‘Machizukuri’ is translated by most commentators as ‘place or city making’ and mainly refers to the direct participation of citizens into urban planning and construction. The present paper discusses the concept and evolution of machizukuri from a social movement to ‘soft-infrastructure’ at city level, focused on serving community needs in post-disaster settings. The 1995 Great Hanshin-Awaji Earthquake in Kobe is chosen as the main case study, in order to review the role and process of machizukuri in disaster management in the context of urban renewal. This is followed by a discussion on the possibility of replicating this model in other contexts and the challenges which machizukuri and similar bottom-up groups are faced with in ensuring their sustainability. The paper argues that the culture and personal engagement of the citizens, and the commitment of national and local governments to cooperate with civil society groups, are essential in this process. Finally, the study suggests that the utilization of this concept has proved that there are undeniable benefits in engaging civil society in decision-making processes and initiatives, with the ultimate aim to create communities capable of overcoming the catastrophic consequences of disasters.

Experimental studies of seismic soil pressures on vertical flexible, underground structures and analytical comparisons

Seismic soil pressures are critical analysis components to understand and design for soil-structure interaction of sub-surface structures. A large scale experimental research program conducted at E-Defense's Shake table in Miki, Japan, included unprecedented seismic soil pressure measurements on a vertical, flexible, hollow shaft with model scale dimensions of 0.8 m square and 7.0 m in height. The densely instrumented vertical shaft was part of a larger system of underground structures, placed in an 8.0 m diameter laminar soil box. The two-layer soil stratigraphy consisted of an upper layer of medium dense sand and a lower layer of simulated bedrock. The hollow vertical shaft was constructed of aluminum and scaled to 1/20th of its prototype dimension. Two-directional, scaled ground motions of the 1995 Kobe earthquake were applied via shake table loading and seismic pressures were recorded using contact pressure sensors. Experimental results, including a dynamic system characterization, site response analyses, pressure time histories, and seismic pressure distribution profiles provide a critical benchmark for imminent numerical studies and the advancement of seismic soil pressure models for flexible structures. Following a thorough review of soil pressure analysis methodologies in literature, a detailed description of the large scale test and experimental results is presented. A comparison with limit state and elastic-based analytical approaches for retaining walls found in literature showed that, despite the unique shaft geometry, analytical methods accounting for the structural flexibility were able to closely predict the experimental soil pressures, while methodologies derived for rigid subsurface elements can only serve as rough preliminary estimate and should not be employed in performance based geotechnical analyses.

Shaking Criminal Incentives

We study criminal incentives exploiting the devastating shock of the 1995 Kobe earthquake. Evidence shows that the earthquake decreased burglaries but left other crime types unaffected. The effect stays significant even after controlling for unemployment, policing and income. We corroborate this by instrumenting damages with the distance from the earthquake epicentre. These findings survive various robustness checks under different specifications. The evidence is consistent with a simple theory of crime, value and specialization. We conclude that burglars respond to damages that devaluate their prospective takings. Yet, they cannot shift their specialization and substitute burglaries with other crime types.

Seismic Design of Steel Structures with Special Flexural Frame Based on Performance by Durability Method

Equivalent static, response spectrum and time history analysis are the well-known analysis methods that traditionally proposed. These methods are highly accurate but requires a great deal of time to match accelerations and the number of analyses, in the other words these methods are time consuming methods. Hence recently the structures are investigated using the durability time method, which plays an essential role in reducing the number of analyses that needs to be created; In fact, the durability time method is a new method of seismic analysis that is presented with a minimum number of time histories analysis. In this method the structure is placed under the influence of an increasing dynamic stimulation, structural response has been investigated over time and evaluated according to the corresponding response to different levels of stimulation intensity, strengths and weaknesses, and structural performance. In this study, steel folding frameworks with 5, 10 and 15 floors were investigated under two analytical methods (Time durability and Time histories methods). At first, the frameworks will be exposed under history of Imperial Governor, Kobe and Lumaprita earthquakes and analysis by finite element software ABAQUS. Then, based on the three analytical functions, the durability is investigated and the results are compared with each other. Finally, the behavior of the structures discussion and conclusion. The results show that the durability analysis method for earthquakes with higher intensity and time is more efficient, and for the Time-less earthquakes by time history method parametrically have a parametrical difference of 5%.

Recovery of Stress During the Interseismic Period Around the Seismogenic Fault of the 1995 Mw 6.9 Kobe Earthquake, Japan

AbstractWe analyzed the current stress state on the Nojima Fault, the source of the 1995 Mw 6.9 Kobe (Japan) earthquake, using breakouts in a borehole through the fault to a depth of ~1,000 m in 2017. The main fault was found at a depth of 529.3 m, with a damage zone ~60 m thick. Statistical analysis shows that the maximum horizontal stress (σHmax) in the depths shallower than 500 m rotates counterclockwise with depth toward the fault and reaches 138° at a depth of 500 m approximately perpendicular to the fault, coinciding with that measured in 1997. In the depths of ~650–1,000 m, the σHmax is oriented 241°, closely matching the regional tectonic stress direction. Our results reveal an accumulation of compressive stress, the driving force of faulting in the deep seismogenic zone since the 1995 earthquake, implying the fault zone has been healing continuously throughout the 22‐year postseismic period.

Use of large-scale shake table tests to assess the seismic response of a tunnel embedded in compacted sand

Shield tunnels are widely used throughout the world. However, their seismic performance has not been well studied. This paper focuses on the seismic response of a large scale model tunnel in compacted sand. A9.3 m long, 3.7 m wide and 2.5 m high rigid box was filled with sand so as to simulate the sandy soil surrounding the tunnel. The setup was excited on a largescale shake table. The model tunnel used was a 1:8 scaled model with a cross-sectional diameter of 900 mm. The effective shock absorbing layer (SAL) on the seismic response of the model tunnel was also investigated. The thickness of the tunnel lining is 60 mm. The earthquake motion recorded from the Kobe earthquake waves was used. The ground motions were scaled to have the same peak accelerations. A total of three peak accelerations were considered (i.e., 0.1 g, 0.2 g and 0.4 g). During the tests, the strain, acceleration and soil pressure on the surface of the tunnel were measured. In order to investigate the effect of shock absorbing layer on the dynamic response of the sand- tunnel system, two tunnel models were set up, one with and one without the shock absorbing layer of foam board were used. The results shows the longitudinal direction acceleration of the model tunnel with a shock absorbing layer were lower than those of model tunnel without the shock absorbing layer, Which indicates that the shock absorbing layer has a beneficial effect on the acceleration reduction. In addition, the shock absorbing layer has influence on the hoop strain and earth pressure of the model tunnel, this the effect of shock absorbing layer to the model tunnel will be discussed in the paper.

Earthquake Damages and Disaster Prevention of Aboveground Storage Tanks

Severe damages in aboveground storage tanks (AST) have been often experienced due to earthquakes in Japan. In this paper, earthquake damages of ASTs which occurred for the last several decades are reviewed. These are damages in the 1964 Niigata Earthquake, the 1978 Miyagi Earthquake, the 1983 Sea of Japan Earthquake, the 1995 Kobe Earthquake, the 2003 Hokkaido Earthquake and the 2011 Great East Japan Earthquake. The damages of ASTs can be classified into 3 types in accordance with the characteristics of earthquake. These are the impulsive motion due to a high frequency earthquake, the sloshing motion due to a low frequency earthquake and the tsunami attack. In the impulsive motion, buckling of sidewall plates and uplift of sidewall-to-bottom joints occurred. In the sloshing motion, sinking of floating roofs into liquid and buckling of sidewall-to-roof joints occurred. In the tsunami attack, ASTs moved and overturned to leak oil.

A 1-g shaking table investigation on response of a micropile system to earthquake excitation

Considering the increasing applications of micropile systems in seismically active areas, a better understanding of their seismic performance and the key controlling factors is of high significance. This paper presents experimental investigations of the seismic performance of a small-scale physical model of micropiles under seismic ground motions. Shaking table tests were performed on a 4 × 4 group of vertical micropiles embedded in loose sand. Horizontal acceleration time histories recorded from the 1940 El Centro earthquake and 1995 Kobe earthquake were applied to the base of the soil container. The response of the physical model was monitored in terms of horizontal accelerations at different levels and bending moments induced in the micropiles. The experimental results indicate that in all shaking events, the magnitudes of horizontal accelerations on the soil surface and the pile cap were amplified with respect to the input motion. Bending moments were induced in the micropiles and peaked at the mid-depth. It was also found that inclining the micropiles led to improvement in their seismic performance, reducing both the acceleration response on soil surface and pile cap, and the induced bending moments in the micropiles. Finite element simulations of shaking table tests have been performed, and the results are in reasonable agreement with observations from the experiments.

Experimental and numerical study of I-shape slit dampers in connections

Abstract This paper proposes a new beam to column connection which has slit dampers to increase ductility and moment capacity of structures. After Northridge and Kobe earthquakes, many researchers have tried to achieve more ductile connections. Ductility of connections causes to dissipate more energy before failure of connections. Also, some researchers have tried to find methods that plastic hinge occurs out of the beam to column connection zone. The proposed detail connects beam to column by two I-shape slit dampers. One experimental specimen of the proposed connection was tested under cyclic loading. Based on the experimental results, the connection has high seismic performance and rotational capacity more than 0.04 radians. Also, the slit damper connection has more moment capacity than other common connections and indicates a good hysteretic behavior. Experimental observations showed that no cracks and fractures occurred in welds and high energy absorption of the slit dampers prevented damages of other parts. Also, local buckling didn’t occur on the flanges and web of the beam. The column and beam remain in elastic state. Some numerical models were made in ABAQUS software. Analysis results had good agreement with experimental results and showed high energy dissipation and ductility in the proposed connection.

다크 투어리즘(Dark Tourism)의 부정적 측면에 관한 고찰 : 고베지역 주민을 사례로

The many of residents in Kobe experienced the great earthquake in 1995. Although most of them have suffered from it, many tourists visit Kobe as a tourism destination where they could feel a tragic site of earthquake. It is the terrible and unpleasant situation to local residents; however, lately Dark Tourism has been flourishing as one of alternative tourism in the world.BR The study aimed to examine some negative effects of Dark Tourism from Kobe earthquake on side of local residents. As there are two sides in a coin, Dark Tourism has both, positive and negative effects too. 55 residents in Kobe participated in 3 discussions from January 15 to 19 in 2018 to talk about its uncomfortable stories. They concluded three major negative perspectives such as remembrance of trauma, excessive commercialization, and fallen image of Kobe.BR As a result, changing attitude of visitors is the best solution to cure negative sides of Dark Tourism, along with supporting local residents in medical and social service continuously.

A seismic behavior and numerical model of narrow paneled cross-laminated timber building

A national research project to investigate proper structural design methods for cross-laminated timber (CLT) buildings has been initiated by a subsidiary of the Ministry of Land, Infrastructure, Transport and Tourism of Japan since 2011. In the final stage of the project, shaking table tests were conducted for CLT buildings designed according to a proposed structural design procedure which confirmed damage limit state, safety limit state, allowable stress, and ductile factors, etc.This paper presents results of shaking table testing for full-scaled CLT building and a design procedure. The three different systems examined are buildings composed of narrow panels, wide panels with an edge tensile connection, and wide panels with an edge tensile connection for each no-window shear part. The focus of this paper is the building of narrow panels. This building system is suitable for midrise CLT building with high ductility produced through rocking. The structure was shown to behave well during severe strong motion as specified in the Japanese building standard law and to have survived the 1995 Kobe earthquake despite the occurrence of a compressive rupture in shear walls which are support elements against the vertical load. Story shear capacity calculated from a numerical model and element tests (such as connections) were safely evaluated; but to evaluate the capacity correctly, further research is required in the element and system levels. Though a variety of undetermined issues and challenges remains, the Building Standard Law and Notification for three different CLT construction systems was enforced in April 2016 to ensure the construction of safe CLT buildings.

Return of the inoperability

There has been unrest in the research community investigating the inoperability of an economic system under disaster situations. The inoperability input–output model (IIM), which is very popular in the risk management field, has become a center of argument, particularly from the input–output researchers, that IIM is a straightforward application of the standard Leontief input–output model. This paper revisits the concept of inoperability, rather than IIM, and proposes its new role in disaster impact analysis using a conventional tool, i.e. the RAS method, for illustrating how the inoperability of an economic system in the aftermath of disaster can be evaluated. The proposed framework is employed to examine the inoperability of industries resulting from the 1995 Kobe earthquake. The findings of the analysis reveal the usefulness of inoperability concept that can even incorporate resilience (gained operability) using the proposed framework of this paper.

Recurrent neural network model with Bayesian training and mutual information for response prediction of large buildings

An accurate response prediction model is of great importance in various applications such as damage detection, structural health monitoring, and vibration control. Development of such a methodology for large civil structures is challenging because of their size and complicated behavior and noise-contaminated, nonlinear, and nonstationary nature of the signals. In addition, the prediction model must have a low computational burden for real-time applications. In this article, a new methodology and a nonlinear autoregressive exogenous model (NARX)-based recurrent neural network (NN) model is presented for accurate response prediction of large structures. The methodology is based on adroit integration of three concepts: a recent signal processing concept, empirical mode decomposition (EMD), mutual information (MI) index from the information theory, and a probabilistic Bayesian-based training algorithm. The EMD method is used to remove the noise in the measured signals. An MI index is proposed to determine the optimum number of neurons in the hidden layer of the NN model with the goal of reducing the computational requirements without affecting its performance. Finally, Bayesian regularization (BR) is proposed to train the optimized NN model. The effectiveness of the proposed methodology is assessed by predicting the structural response of a 1:20-scaled 38-story highrise building structure subjected to seismic excitations and ambient vibrations, and a five-story steel frame subjected to different levels of the Kobe earthquake.

A study on both Great East Japan Earthquake and Great Hanshin-Awaji Earthquake to define differences of the plans for commercial accumulation's restoration and revival assistance.

A study on both Great East Japan Earthquake and Great Hanshin-Awaji Earthquake to define differences of the plans for commercial accumulation's restoration and revival assistance.

Failed cooperation in times of natural disasters: explaining the rejection of humanitarian aid

AbstractThis article asks why economically strong democracies reject humanitarian aid after severe natural disasters, focusing on the Kobe earthquake in Japan (1995), India’s response to the Indian Ocean tsunami (2004), and Hurricane Katrina in the United States (2005). It explains these rejections of humanitarian aid by analyzing the decision-makers’ ‘self-perceptions’ through the factors of manageability, national role perceptions, and domestic political impact, as well as ’other-perceptions’ through their relations to donors and the nature of the aid offers. It finds that even in those disaster-prepared and economically strong democracies, state leaders rejected humanitarian aid not simply because they had sufficient disaster management capabilities. Rather, bureaucratic hurdles and administrative failure impeded aid acceptance. Moreover, conceptions of those countries’ roles as established or emerging donors, as well as domestic political factors influenced their decisions. Ultimately, the dominant explanations focusing on wealth and capabilities are thus too shortsighted. Not only giving but also rejecting humanitarian aid follows political considerations.

Late Pleistocene-Holocene activity and paleoseismicity of the Nojima Fault in the northern Awaji Island, southwest Japan

Field investigations and analyses of tectonic landforms show that the topographical markers of terrace risers and alluvial fans formed in the late Pleistocene-Holocene have been systematically offset by ~40–62 m along the Nojima Fault on which the 1995 Mw 6.9 Kobe earthquake occurred. Analysis of tectonic landforms, trench excavations, and radiocarbon dating results reveal that i) at least two large earthquakes prior to the 1995 Mw 6.9 Kobe earthquake occurred in the past ~1800 years; ii) the most recent event occurred in ~1000 CE, and the penultimate large earthquake event took place in ~200 CE, suggesting an average recurrence interval of ~900 yr for large earthquakes on the Nojima Fault. Based on the deformation features of tectonic landforms and radiocarbon dating ages, the late Pleistocene-Holocene strike-slip right-lateral rate is estimated to be ~2.0–3.0 mm/yr with an average of 2.5 mm/yr for the Nojima Fault. These findings show that previous studies had significantly overestimated the recurrence interval and underestimated the slip rate of the Nojima Fault. Accordingly, the Nojima Fault poses a much greater seismic hazard than previously believed, and therefore, it is necessary to reassess the potential seismic hazard for the densely-populated Awaji-Kobe regions, southwest Japan.

Transportation simulator for disaster circumstance and bottleneck analysis

In recent years, massive earthquakes struck Japan, causing large-scale disasters such as the great Hanshin-Awaji earthquake in 1997, the Niigata Prefecture Chuetsu earthquake in 2004, the great east Japan earthquake in 2011, and the Kumamoto earthquake in 2016. In the all disasters above, logistics system for relief supplies collapsed and it was repeated that the relief supplies were not delivered properly to the evacuation refugees. The cause of repetition of this situation is the lack of knowledge to estimate the capability of the logistics system in the disaster response plan, which may constitute a part of disaster prevention plan. In this paper, two analysis tools are introduced. One is a simulator based on the multi-agent system, in which the vehicles, e.g., trucks, ships, aircrafts, as agents determine their delivery destination corresponding to sufficiency ratios of the relief supplies of respective evacuation centers. The other is an analytical solution to estimate transportation capability.

Disaster Response Research Development in Japan

Japan is a country of natural disasters and many lessons have been learnt in the past. The Disaster Medical Assistant Team (DMAT) system is one of those. After the 11 March 2011 Great Eastern Japan Earthquake and Tsunami, Japan experienced unprecidented disturbance of people’s life including distruction of infrastructures, mass evacuation and collapse of communities. Everything went mess from immediate shortage of life supporting facilities to loss of future prospects. The importance of the unified command system is also a lesson learned from the past disasters such as the Kobe earthquake. However, there is still a gap in tools for decision makers to acquire timely information about public health status of affected areas. For example, there are no standardised tools to evaluate the consequences of long-term evacuation on emotional and physical health. The lack of such epidemiological instruments makes it difficult to perform evidence based public health. Absence of such tools may also have hampered the participation of public health specialits into disaster response teams. In Japan, the government moved to establish a public health response team, namely Disaster Health Emergency Assistance Team or DHEAT, in order to quickly provide prompt public health survices during and after the disaster. To add an environmental component to such an effort, the National Institute for Environmental Studies started a programme to implement epidemiological tools that can be readily used from immediately after the disaster onset to decades long recovery periods for assessing general and specific environmental exposures and their effects on affected people. This presentation will focus on the Japanese endeavour to develop disaster epidemiology tools and its collaborative works with the US National Institute of Environmental Health Sciences.

Financial Imbalances in Regional Disaster Recovery Following Earthquakes—Case Study Concerning Housing-Cost Expenditures in Japan

In the aftermath of the 1995 Kobe Earthquake, a large-scale effort towards reconstruction of houses damaged by the quake was required. This led to increased mortgage, thereby financially plaguing a number of earthquake victims and inhibiting their long-term sustainability and self-supported recovery. The current framework of housing reconstruction assistance provided by the Japanese government does not account for regional disparities in cost and other socioeconomic factors. This study proposes a technique for estimating the cost of reconstructing household units damaged in an earthquake by considering the effects of construction methods influenced by regional climatic zones. The financial constraints on rebuilding resources have been estimated by considering the annual regional income and household savings, as determined by social factors and employment opportunities. The susceptibility of regions to the occurrence of earthquakes has also been factored in the calculation of recovery costs. Together, these factors are used to provide a more complete picture of economic costs associated with earthquake recovery in different regions of Japan, thereby revealing large disparities in the difficulty and financial burden involved in the reconstruction of household units. Results of this study could be used to develop a robust system for earthquake-recovery assistance that accounts for differences in recovery costs between different regions, thereby improving the speed and quality of post-earthquake recovery.

Analysis of the Kobe earthquake time series via system identification and fault-detection techniques

The Kobe earthquake was one the most severe earthquakes in Japan in recent years. It occurred on January 16, 1995, at 20:46:49 (UTC) and measured 6.8 on the moment magnitude scale. In this paper, the time series of the unbiased earth ground vertical acceleration collected by a seismograph located at the University of Tasmania, Hobart, Australia, is analyzed. The time series is segmented into three consequent sub-series which represent the normal seismic activity before the arrival of the earthquake, a transition phase, and the arrival of earthquake waves. The analysis is separately performed for each segment. We show that by inspecting the degradation of the prediction performance of the model identified based on the normal seismic activity data set, it is possible to distinguish between the transition phase and normal seismic activity about 200-300 seconds before the beginning of the earthquake phase. Though this does not mean that earthquakes can be forecasted, because of the significant data distortion due to the long distance between the epicenter and the data collection location, nevertheless the achieved result may open up new routes in the study of earthquakes.